Food container



E. F. KOHMAN FOOD CONTAINER Filed April 10, 1928 Dec. 5, 1931.

Patented Dec. 15, 1931 UNITED STATES PATENT oFFIc-E j EDWARD F. KOHMAN, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR T NATIONAL CANNERS ASSOCIATION, OF

CORPORATION 0F DELAWARE FOOD CONTAINER Application med April 1o, 1928. serial No. 27i,417.

This invention relates to food receptacles, and more particularly to an improved container for canned foods.

@ne of the sources of losses in the producat tion and distribution of canned foods is the so termed hydrogen swells.

These swells are caused by corrosion of the can and the consequent evolution of hydrogen. As is known when a. metal, such as iron, dissolves in acid an equivalent amount of hydrogen is evolved. The losses arising from hydrogen swells, therefore, are of particular importance in the canning of acid foods, such as fruit products.

llt is an object of this invention to provide a metallic container which minimizes the formation of hydrogen. A

Another object of this invention is to provide a food container which comprises met ais of different electro-chemical characteristies.

A further object of this invention is to provide a container in which perforations are minimized.

Yet another object is to provide a container which comprises metals of different physical properties.

A further object is to provide a novel can top adapted for use with a tin can.

lvl/lith these and other equally important objects in view, the invention comprehends the provision of a can, comprising a body and ends of metals of different characteris tics, and which are so related as to minimize perforations and the formation of hydrogen.

The invention is illustrated diagrammatically in the single figure of the'accompanying drawing. In this the numeral A represents a can body of the usual type and B indicates a covering composed of a softer metal than the metal comprising the body. Thus the covering B provides an end or top for the can.

it has longr been known that pciforations resulting from various fruits in enameled' cans occur very largely at the countersunk end of the can. It has been assumed that the source of hydrogen formation is this countersink portion, since Jit is at the point Where the perforatlons occur.

WASHINGTON, nrsfriuor or COLUMBIA; A

As a result of extended experiments', I have found that a large part of the hydrogen and, in some instances, the majority of it may be the result of vcorrosion at oints of the can other than the countersin The portions where the corrosion usually centers is on that section of the can body which projects into the double seam and is adjacentto the countersink on the end. The .corrosion at this point is more pronounced when a rubber com? v pound lining is used than is thecase Where a paper gasket is employed.

These observations clearly indicate that corrosion on the body of the can is dueto the injury received, or the strainedA condi-I tion resulting from the stresses imposed during the double seaming operation. Thisinpiry as has been stated, may bediminished by interposing a member, such as aA paper gasket, which provides a padding or buffer y effect.

I have found that the generation Yof hydrogen is initiated considerably sooner, and itsdeleterious efi'ects made quickly manifest, 1f

the deformation of the can body is accentuaied, as evidenced by the following experiment. A certain number of tin cans of the usual type were filled with red raspberries.

Cans of this type of fruit, as is Wellknown,

are not particularly susceptible to hydrogen formation. These cans were then sealed with stainless steel tops. These tops, as will be understood, are not corroded by red raspberries oi by any of the other acid food products. This metal, it will be noted, is of a stiffer or harder character than the metal of the can body. After a period of three months, each of these cans had become a .hydrogen swell. The significance of the factor will be fully appreciated when it is consideredthat similar cans, with a tin plate top, generally show no hydrogen formation for a lperiod consi derablyv more than a year. Y

he cans used in this experiment were opened and it Was then found that the corrosio'n noticed in enameled tin cans of this type Was greatiy augmented. Uponexarnination of' the seams, it Was immediately evidenced that the rules which were yformed on the edge of the end from the first operation of the double seamer, caused indentations in the contiguous section of the body of the can. These indentations were plainly visible to the naked eye.

This deformation of the metal of the can body disrupted the enameled inside surface of the can, and corrosion started at, and s read from, these points. It was noted that tliese indentations were similar although much augmented to indentations that are sometimes noticeable on ordinary commercial cans. From an inspection of a number of commercial cans, at different stages of storage, it appears that the corrosion initiates at the protuberances or indentations caused by the double seeming operation and emanating from these points merges into a band of corroded area encircling the entire can near the edge.

I have found that this deformation of the can and its concomitant disadvantages may be avoided by providing a can body which will not deform when it is seamed in. This as shown in the drawing may be accomplished in two general ways; first, by providing a top or cover`which is of a softer or more deformable material than the can body, or by making the can body itself of greater rigidity or stiffness than has been Fdone heretofore. Whether the can body and its ends are constructed of the same material but of varying thickness, or whether the can body is constructed of one metal or alloy and the deformable top of a different metal or alloy, it will be appreciated that the body of the can is heavier than the ends or top, inasmuch as the former offers reater resistivity to deformation than the atter portion. It is to be understood that the word heavier is employedl in this sense in the claims appended ereto.

The advantages of this invention may be secured by utilizing an aluminum or aluminum alloy top in conjunction with a can body of the usual type. As is known, aluminum material, and many other alloys, is much softer than the ferru 'nous base plate and, hence will distort beixe the can body. It will immediately be perceived that by utilizing such a top any deformation incident to the seaming operation will be limited to or concentrated in the top.

Aluminum and aluminous alloys are particularly well adapted to the present use. In its electro-chemical effect in relation to the iron of the base plate, aluminum is comparable to tin. The electro-chemical effect of tin in a tin can is to inhibit the corrosion of iron, while on lthe other hand the corrosion of tin is augmented as a result of being in contact with iron. The corrosion of tin, however, is exceedingly small, since the area of iron which is exposed as compared to the area 0f tin is quite small. As will be seen from an inspection of the following tables the corrosion test with aluminum and base plate disclose a similar relationship existing between aluminum and iron, as that which obtains `between tin and iron. The corrosion of iron is inhibited by virtue of its being in contact with aluminum. It is particularly to be noted that aluminum possesses an advantage over tin in the fact that the corrosion of aluminum is not increased by contact with iron in the base plate. It will be seen, therefore, that an aluminum end on a tin plate body will have a beneficial electro-chemical effect. As has been noted hereinbefore, the softness of aluminum and its alloys will prevent injuring of that portion of the tin plate-body which enters into the double seam.

Loss in milligram or spec/mens of alu/miam and of aluminum alloy 52 l/.QXl om. n dimension both when alone and also when n electrical contact with tron amil eposeal to red raspberries as the corrosive medi/wm 210 hours 523 hours 1195 hours A No con- No con- N o contact Contact met Contact tact Contact Fe Al Fe Al Fe Al Fe Al Fe Al Fe Al ALUMINUM ALLOY (containing about 1%% manganese) ALUMINUM It will be observed from the foregoing table, that by reason of being in contact with l aluminum, the corrosion of iron is greatly diminished; for example, a specimen of iron base plate which was contacted with red raspberries as the corrosion medium lost 3.9 milli grams in approximately 22 days, whereas this material in contact with aluminum lost only 2.2 milligrams due to corrosion. The effect when using both aluminum and an aluminum alloy is particularly noticeable after the spec imens have been in cont-act with the corrosion medium for a longer period. After an exposure of approximately 50 days, thecorrosion of iron was diminished from 10.1 to 3.9, and from 11.2 to 7.0 milligrams when contacted with aluminum alloy and aluminum, respectively.

The table is given purely by way of example to typify the general relationship which exists between the iron' base plate and material of an aluminum-like nature. It will be appreciated that there are a number of specific metals and alloys which possess similar characteristics, in respect to their ei'ect upon iron, All such metals and alloys are nav/',051

comprehended Within the spirit and scope of the present invention.

Aluminum and its alloys possess another decided advantage for the present use. To 'these materials enamel adheres very satisfactorily, in fact, in some cases the adherence is even better than the adherence of enamel to tin plate. This is of particular importance because of the fact that in the present practice those cans which are designed to contain colored acid foods are coated on the interior with an enamel.

Itis to be noted that the advantages of the invention are secured Vat a reasonable cost. While it is true that aluminum sheets or aluminum alloys cost somewhat more than tin plate, the Weight of tin plate is approximately 21/2 times that of aluminum. Since these materials are bought by Weight, it will be seen that the price of a given quantity of aluminum is about 21/2 times less than that of tin plate.

As has been intimated hereinbefore,the advantages of the invention may be secured not only by providing a top which is of a softer material than the body portion, but also by making up the cans in the Ordinar way but using a base plate of increased sti ness, that is to say, by constructing a can in which the base plate used in the body portion is stifer lor heavier than that used for the top. In this manner, when the can is subjected to the double seaniing operation the metal of the top Will be selectively deformed, and corrosion of the body at the place indicated will be prevented. It is to be observed that in lieu of making the base plate of the body of a heavy material, it may be constructed of the same quality as has been done hereinbefore and the can may be capped with a tinbase plate which is of a lighter or less resistive character than the base plate used in the body. y

The invention resides in the broad concept of providing a can in which the top and body portions are of different degrees of softness, so that when the pressure incident to the .scaming operation is applied, the top of the can will be deformed, and the body retained substantially in its initial condition.

While I have shown and described thespecific embodiments of the invention, it is to be rigid outside sustaining ends to the cam body, said ends being of softer metal than the body portion of the can.

2. A metal can for containing food products comprising a ferrous body portion enameled on the interior, rigid outside sustaining ends for the can, interfolded seams joining the rigid outside sustaining ends to the can body, said ends being of softer metal than the body portion of the can.

3. A metal can for containing food products comprising a ferrous body portion, a thin tin coating on the interior of the can body, rigid outside sustaining ends for the can, interfolded seams joining the ri id outside sustaining ends to the can bot y, said ends being of softer metal than the body portion of the can.

4. A metal can for containing food products comprising a ferrous body portion, a thin acid-proof coating on the interior of the can body, rigid outside sustaining'ends for the can, interfolded seams joining the rigid outside sustaining ends to the can body, said ends being of an aluminous metal which is softer than the body portion of the can.

5. A metal ca'n for containing food products comprising a ferrous body portion enameled on the interior, rigid outside sustaining ends forthecan, interfolded seams joining the rigid Voutside sustaining ends to the can-body, said ends being of an aluminous metal which is softer than the body portion of the can.

In testimony whereof I affix my signature.

EDWARD F. KOHMAN.

understood that these are given merely by way of example, for', as has been indicated, the purpose may be eifectuated by utilizing a number of different materials, hence, I do not intend to be limited to those described, except as such limitations are clearly imposed by the appended claims.

I claim:

l. A metal can for containing food prodi 

